A report highlights concerns raised by urine samples and shows that the game is struggling to implement meaningful out-of-competition blood testing
Footballers across the world produced 250 urine samples which led to further investigation by drugs testers in 2012, according to the latest figures from the World Anti-Doping Authority (Wada).
A total of 27,177 samples were analysed during the year with 5,041 of that number coming out of competition.
Of those, 250 raised suspicions due to adverse findings which either required a satisfactory explanation or led to further action, such as disciplinary proceedings by relevant governing bodies.
In the report released this week, however, Wada did not specify the outcome of the investigations into the flagged samples.
Only three per cent of anti-doping tests carried out across the game in 2012 used blood samples and of those none were failed.
Fifa conducted only four out-of-competition blood tests during the entire year but Uefa did better with 132 in-competition blood tests conducted as well as 191 conducted out of competition.
Many prominent national football associations, including those of Brazil, Germany, Spain and the Netherlands, failed to analyse one blood sample of any player during the year, according to Wada.
Indeed only Italy, France, Portugal, Romania, China, Poland and Austria - along with the UK's investigators - carried out any blood sample analysis in 2012.
In all, 28,008 anti-doping tests were conducted across the world of football last year with only 831 of that number being blood tests. Less than half that number - 346 - were out-of-competition.
Many experts believe tests of this kind are the most effective method of detecting controlled substances. The International Olympic Council president, Jacques Rogge, called in May for more such tests to be conducted.
Meanwhile, testing for the banned blood booster EPO in football produced no adverse findings from a total of 1347 in-competition tests and 728 out-of-competition tests.
In February the Wada president, John Fahey, told Goal that football was not doing enough to combat EPO blood doping.
Football's fight against the issue has, according to Fifa, intensified in 2013 with the introduction of the Athlete Biological Passport for every competitor at the recent Confederations Cup and plans afoot for every player at the 2014 World Cup to undergo the same procedure.
The Athlete Biological Passport, according to Wada, "monitors selected biological parameters over time that reveal the effects of doping rather than attempting to detect the substance itself."